After their arrival on Christophsis, Slick's unit reconnoitered the planet and located a double-towered business complex as a suitable site from which to ambush the Confederate droids. While returning to the Republic base, the platoon came across a group of B1 battle droids that were attempting to clear a major boulevard of Christophsianrefugees. When the battle droids found a crippled Christophsian and proposed killing him, the clones intervened and eliminated the droids before returning to the base.[8]

Sketch and Punch served as each other's alibis.

Later, Sergeant Slick's platoon was stationed in the business building's south-facing tower with General Kenobi and Clone CommanderCC-2224, while Skywalker and Clone CaptainCT-7567 were based with their soldiers in the parallel north tower. The Republic troops prepared to attack the Confederate droids below, but the approaching droid column unexpectedly split in two, and battle droids arrived in the south tower and ambushed the clones. Skywalker and his men arrived in the south tower to reinforce Kenobi's group, and after taking a turbolift to the roof of the tower, the Republic forces escaped in clone pilotHawk'sLAAT/i gunship.[3]

After the Republic forces had returned to their base, Sketch and fellow platoon member Punch went to the mess hall,[3] which they habitually frequented.[1] During investigations regarding the possibility of a Confederate spy amongst their ranks, CC-2224 and CT-7567—nicknamed "Cody" and "Rex," respectively—traced an irregular wavelength in external communications to Slick's barracks. Suspecting that one of the sergeant's men was the enemy agent, the two clone officers called the platoon back to its quarters to individually interrogate its members. Sketch vouched for the nervous Jester and verified his alibi, and Sketch and Punch supported each other's claims that they had been in the mess hall. When trooper Chopper stated he had also been in the mess hall with them, Sketch refuted his claim. With encouragement from Cody, Sketch revealed that Chopper had not arrived to the mess hall until later in the evening. However, Slick was eventually revealed to be the spy, and escaped before severely damaging the Republic's gunships, AT-TE walkers, and weapons depot. When Slick was spotted running into the base's command center, and Rex and Cody ordered Slick's platoon to secure the perimeter. The two clone officers later managed to apprehend Slick.[3]

A Human male, Sketch had tan skin, black hair, and yellow eyes and stood 1.83 meters tall.[1] He had a tattoo of the Aurebesh letter Senth, or "S," above his left eye.[2] During the Battle of Christophsis, he frequented the Republic base's mess hall with fellow trooper Punch to the point where it became a habit.[1] In the course of investigations into a possible traitor within his unit, Sketch verified Jester's claim and noted his fellow trooper's "obsession" for always cleaning his blaster after every battle.[3] His keen observation skills helped Cody and Rex eliminate suspects and zero in on the real traitor.[1] When Chopper claimed to be in the mess hall, Sketch objected to his statement but then stopped, only continuing with persuasion from Cody. Sketch was later shocked when his own sergeant, Slick, was revealed to be the turncoat.[3] He was trained for combat, and his clone armor's greaves were dingy with grime from fighting.[1]